Low solvent and solvent-free two-component polyurethane lacquers are known (see e.g. German Auslegeschrift No. 2,006,055, German Auslegeschrift No. 2,304,893 or Canadian Pat. No. 1,029,890). One major disadvantage of these two-component systems is their limited pot life.
One-component binders based on organic isocyanates which have a virtually unlimited storage life in the absence of moisture and can be used for the preparation of solvent-free or low solvent lacquers which can be applied by any of the conventional methods of lacquer technology and are hardened by atmospheric moisture have not hitherto been known. The known one-component systems based on isocyanates, i.e. the known prepolymers containing isocyanate groups, generally have too high a viscosity for application by, for example, spraying without the use of a solvent.
It was an object of the present invention to provide such one-component binders. It could be solved by means of the isocyanate mixtures described in detail below.